The Pitti Tondo, one of the most celebrated and most beautiful works of Fra Filippo was executed in about 1452. He began to fresco the enormous choir of the Cathedral of Prato in 1452 (after Fra Angelico had turned down the assignment). He was aided by his chief assistant of the period, Fra Diamante; the work dragged on for years. In Prato Lippi also obtained a number of other assignments (such as the Madonna del Ceppo and the Madonna della Cintola) and purchased a house there in 1455. By 1458 he completed a painting for the king of Naples, a commission negotiated by the Medici, for whom Filippo produced an Adoration of the Child in c. 1460.